致密及页岩气藏气井分段压裂返排优化模型与分析  

Staged fracturing flowback optimization method for horizontal wells in tight and shale gas reservoirs

作　　者：王瑞[1,2] 张瑞超[1] 贾潇 黄航娟 任斌 池晓明 袁晨雨 ANG Rui;ZHANG Ruichao;JIA Xiao;HUANG Hangjuan;REN Bin;CHI Xiaoming;YUAN Chenyu(College of Petroleum Engineering,Xi’an Shiyou University,Xi’an 710065,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology),Chengdu,610500,China;The Sixth Oil Production Plant,PetroChina Changqing Oilfield Company,Xi’an 710018,China;Changqing Downhole Technology Company,Chuanqing Drilling Engineering Co.,Ltd.,Xi’an 710034,China)

机构地区：[1]西安石油大学石油工程学院,西安710065 [2]油气藏地质及开发工程国家重点实验室(成都理工大学),成都610500 [3]中国石油长庆油田分公司第六采气厂,西安710018 [4]川庆钻探工程公司长庆井下技术作业公司,西安710034

出　　处：《非常规油气》2023年第5期97-103,共7页Unconventional Oil & Gas

基　　金：国家自然科学基金资助项目“页岩及其矿物和有机质成分对多组分气体的吸附与解吸附机理研究”(51374172);油气藏地质及开发工程国家重点实验室(成都理工大学)开放基金项目“页岩气储层气-液-固界面解吸和液体渗吸相互作用机制研究”(PLN2021-24);大学生创新创业训练计划项目“致密及页岩气藏解水锁剂性能评价和注入工艺设计”(202110705004);西安石油大学青年科研创新团队项目“复杂地层钻采工程力学行为表征及控制理论与技术”(2019QNKYCXTD04)。

摘　　要：致密及页岩气藏气井压裂后的返排质量好坏极大地影响最终的压裂效果,目前此方面的建模未考虑到返排时的井筒内气液两相流和分段压裂多段同时返排的特点。该文对致密及页岩气井的分段压裂裂缝闭合前后的返排特点进行了分析,建立了气井压裂返排、裂缝体积变化和滤失量耦合模型,进行了实例计算分析,讨论明确了裂缝闭合前分段压裂多段同时返排优化方法,并对返排率的计算和基于储层伤害的分段压裂返排优化进行了分析。研究发现:对气井,有地层气体进入返排液时,返排的时间将增长,且在返排后期排液量增幅变小,累积返排液量较大;裂缝闭合前分段压裂多段同时返排优化时,返排量、多条裂缝体积变化和多条裂缝滤失是通过最后一条裂缝出口处的压力耦合起来的;裂缝闭合前后的返排模型的衔接,主要明确了初始井底流压为裂缝闭合前的终态井底流压,初始含水为裂缝闭合前滤失进储层的返排液;将致密及页岩气储层的水锁以及在压裂返排时的水锁自解除现象和机理,与气井压裂返排过程和分段压裂水平气井返排优化结合,以进行致密及页岩气井返排伤害的模拟,但具体实现还待进一步研究。The flowback of fracturing fluid is an important step in the fracturing operation of gas wells in tight and shale gas reservoirs.Whether the fracturing fluid can be discharged smoothly and timely has obvious influence on the construction effect.The characteristics of horizontal well flowback during staged fracturing have not been clearly reflected in the study of drainage.In this paper,the flowback characteristics of tight and shale gas wells before and after fracture closure are analyzed,and the optimization methods of single flowback and simultaneous flowback of multiple stages before fracture closure are established,and the calculation of flowback rate and the flowback optimization method based on reservoir damage are discussed.Results indicate that:the flowback rate,the volume change of multiple fractures and the pressure of multiple fractures filtration through the outlet of the last fracture are coupled when multiple stages are optimized for flowback at the same time before fracture closure.The connection of the flowback model before and after fracture closure is mainly to determine that the initial bottomhole flow pressure is the final bottomhole flow pressure before fracture closure,and the initial water cut is the flowback fluid filtered into the reservoir before fracture closure.The phenomenon and mechanism of water lock in tight and shale gas reservoirs and self-release of water lock during fracturing flowback are combined with the fracturing flowback process of gas wells and the optimization of horizontal gas well flowback of staged fracturing to simulate the damage of tight and shale gas flowback,but the specific realization needs further research.

关 键 词：页岩气 分段压裂 返排 裂缝闭合 储层伤害 

分 类 号：TE312[石油与天然气工程—油气田开发工程]